Information storage devices are used to retrieve and/or store data in computers and other consumer electronics devices. A magnetic hard disk drive is an example of an information storage device that includes one or more heads that can both read and write, but other information storage devices also include heads—sometimes including heads that cannot write.
In a modern magnetic hard disk drive device, each head is a sub-component of a head gimbal assembly (HGA) that typically includes a suspension assembly with a laminated flexure to carry the electrical signals to and from the head. The HGA, in turn, is a sub-component of a head stack assembly (HSA) that typically includes a plurality of HGAs, an actuator, and a flexible printed circuit. The plurality of HGAs are attached to various arms of the actuator, and each of the laminated flexures of the HGAs has a flexure tail that is electrically connected to the HSA's flexible printed circuit.
Modern laminated flexures typically include conductive copper traces that are isolated from a stainless steel structural layer by a polyimide dielectric layer. So that the signals from/to the head can reach the flex cable on the actuator body, each HGA flexure includes a flexure tail that extends away from the head along the actuator arm and ultimately attaches to the flexible printed circuit adjacent the actuator body. That is, the flexure includes traces that extend from adjacent the head and terminate at electrical connection points at the flexible printed circuit. The flexible printed circuit includes electrical conduits that correspond to the electrical connection points of the flexure tail.
Since the conductive traces of the flexure are separated from the structural layer by a dielectric layer, electrical capacitance exists between the conductive traces and the structural layer. Electrical capacitance also exists between one conductive trace and another adjacent conductive trace. Such electrical capacitances affect the capacitive reactance and impedance of the conductive traces, and hence the bandwidth of the conductive traces.
Heat Assisted Magnetic Recording (HAMR) uses a pulsed laser diode as a heat source on the head. In HAMR applications, the conductive traces connecting the head and the preamplifier of the flexible printed circuit of the HSA require at least two high bandwidth transmission paths: the magnetic write path and the pulsed laser path. Other conductive traces may carry signals from the read transducer (e.g. a tunneling magneto-resistive sensor), to a head-based microactuator, and/or to a resistive heater for dynamic flying height control. Hence, there is a need in the art for a flexure design that can provide required transmission paths on the flexure tail for modern HAMR or non-HAMR applications, without the flexure tail becoming too wide, and with the transmission paths having adequately high bandwidth without excessive crosstalk or excessive impedance.